A frictionally driven elevator is described in EP-A1-0870718 in which a drive wheel and a support wheel are rotatably mounted on levers which are pivotally attached to a lower yoke of a car frame. A compression spring biases the support wheel towards the drive wheel, thereby clamping a track therebetween. The compression spring provides a constant normal force to ensure that there is sufficient frictional engagement between the drive wheel and the track during all operating conditions. This constant normal force is determined from the critical operating condition when the elevator car is fully loaded and moving upwards at maximum acceleration.